This invention relates to an insertable hammer drill, or an insertable chisel, for power-driven drill or chisel hammers. The drill, or chisel, has an insertion end, a shank attached to the insertion end, and a drill or chisel head attached to the shank and located opposite the insertion end
In addition, for example, to the configuration of the cutting edge and to the material used, the shape of the shank of a chisel is also critical for the effectiveness of the latter. DE 40 24 650 A1 discloses, for example, a chisel in which the diameter of the chisel shank narrows in steps from the insertion end toward the chisel tip, and, in this case, a contraction may also be provided. Furthermore, DE-UM 92 09 647 discloses a chisel which is produced as a forged part and the shank of which narrows conically toward the working end and may likewise have a contraction. DE 199 14 522 A1 discloses a chisel with a hexagonal insertion end which has a collar between the insertion end and the shank. This collar has purely the function and action of an abutment. The disadvantage of the two known chisels mentioned first is that the diameter of the shank narrows toward the chisel cutting edge and the stability of the chisel shank decreases continuously or in steps toward the working end. A shaping of this kind is critical, in particular, in the case of chisels with a medium and smaller initial diameter of the chisel shank and in the case of chisels with long chisel shanks, since, as a result of the narrowing, a chisel shank diameter is quickly reached which, because of the minimum mechanical requirements to be met by the chisel shank, is within a critical range and counteracts unintended vibrations to only a slight extent. These considerations also apply similarly to hammer drills as regards their hammering or chiseling property. In the field of drills, what may be referred to as collar drills are known (see, for example, DE 43 22 588 A1, FIG. 3), which have a thickening in the shank region or spiral region. This thickening is co-ordinated in its position with the drilling depth provided. The size and shape of this thickening are aimed at taking as great a care as possible of the workpiece to be machined when the desired drilling depth is reached.